Grammar · Free lesson
TOEIC word families: efficiency, efficient, or efficiently?
A delivery company changes its routing system. You want to describe its efficiency, say that the system is efficient, or explain that it routes deliveries efficiently. The shared meaning stays related, but the sentence job changes.
Professor Scott MendozaThe short answer
Efficiency is a noun naming the quality of working with little waste. Efficient is an adjective describing a person, thing, or process. Efficiently is an adverb describing how something is done. Compare “the efficiency of the system,” “an efficient system,” and “the system works efficiently.”
Find the grammatical job before choosing the word form.
In “the efficiency of the system,” the slot names a quality, so it needs the noun. In “the system is efficient,” the adjective describes the system. In “the system routes deliveries efficiently,” the adverb describes the action. Read the whole phrase rather than relying on the nearest word alone.
One family, three jobs
The new schedule improved the efficiency of the service.
The new routing system is efficient.
The system routes deliveries efficiently.
Efficient does not simply mean fast. A process can be quick but waste fuel or effort. This word family concerns how well resources such as time and energy are used.
Read the slot in its phrase
Name a quality
the efficiency of the service
Describe a thing or action
an efficient service / the team works efficiently
Try it now
Match the form to the job
Read all answers and explanations
Which sentence correctly names the quality after the?
The manager praised the efficiency of the system.The efficiency of the system is a noun phrase. Efficient and efficiently cannot fill that noun slot here.
Which sentence describes the system with an adjective?
The new routing system is efficient.Efficient describes the system. The quality noun does not express that description, and the adverb leaves this sentence incomplete.
Which sentence describes how the system routes deliveries?
The system routes deliveries efficiently.Efficiently describes the action routes deliveries. The noun and adjective do not perform that job in this sentence.
Put it into practice
Repair a workplace report
The report needs a noun naming the quality of the service.
The revised schedule improved the efficiently of the service.
See a model answer
The revised schedule improved the efficiency of the service.
The form follows the noun phrase structure. Adding -ly because the sentence contains a verb would not solve the problem.
A little more clarity
Common questions
A few useful details before you move on.
Does every adverb end in -ly?
No. Fast can function as an adverb without -ly. Learn this family’s forms without turning its spelling pattern into a rule for every word.
The printer works fast. The team works efficiently.
Can I choose just by translating the meaning?
No. Related forms share meaning but fill different sentence roles. Check the phrase around the blank as well.
efficiency → a quality; efficient → a description; efficiently → how an action happens
Take it into your day
The meaning connects the family; the sentence role selects the form.
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